Selection in a provenance trial of Norway spruce (Picea abies L. Karst) produced a land race with desirable properties

Selections were made within East European Norway spruce provenances in a provenance trial in northern Sweden and the selected clones were grafted in a Norwegian seed orchard mixed with plus trees of local origin. Full-sib families were generated by controlled crosses, producing sets of both inter- and intraprovenance families, which were planted in two short-term and in long-term trials. Measurements were made of frost damage, tree height, annual shoot growth rhythm and lammas shoots, and genetic parameters were estimated. The intraprovenance families from selected trees of East European origin showed the least variation in all traits and had the lowest heritability values. The variation among the intraprovenance families of local origin was large and with the highest estimates of heritability. The means of the provenance hybrid families were intermediate between those of the intraprovenance families. Strong genetic correlations were present between the growth rhythm traits measured, and in the family group of local origin also between these traits and frost damage, as well as for lammas shoots and height. The progenies of the selected parents of East European origin seem to be a desirable land race with less damage, lower percentage of lammas shoots and less variability in growth capacity.     

Multi-locus Sequence Analysis (MLSA) of Edwardsiella tarda isolates from fish

Edwardsiella tarda is an enteric fish pathogen that has caused significant economic losses in a range of fish species residing in diverse ecological conditions. Several molecular methods relying on DNA fingerprinting (RAPD, RFLP and ERIC-PCR) and the gyrB gene marker have been used to characterize E. tarda isolates. However, all had drawbacks in resolving power and reproducibility. The present study was aimed at developing a novel Multi-locus Sequence Analysis (MLSA) scheme for genetic characterization of E. tarda isolates originating from multiple sources. MLSA has been described as an effective molecular tool with superior discriminatory power and reproducibility for exploring intra-species genetic diversity of several bacterial species. Nucleotide sequence fragments of eight protein coding housekeeping genes (gyrB, mdh, adk, dnaK, phoR, metG, pyrG and aroE2) were obtained from 23 fish pathogenic E. tarda isolates of different geographical origins, one human isolate and 3 reference strains. The phylogenetic relationships between isolates in individual gene analyses were not consistent, although some common patterns were apparent. Phylogenetic analysis based on concatenated sequences of seven gene loci, however, buffered the conflicting phylogenetic signals and resolved isolates according to their geographical origin and/or fish host. The MLSA revealed two major genetically diverging clusters in E. tarda isolates examined, one cluster representing isolates from fish and the other representing (in the main) human isolates, with E. ictaluri cluster situated in between. The results suggest, therefore, that the fish pathogenic E. tarda isolates may have been previously misclassified and probably represent one or more as yet unrecognized taxa within the genus Edwardsiella. The MLSA described here was robust enough in discriminating E. tarda isolates not only with respect to their geographical origins but also within different hosts from the same geographical location, high-lighting its potential application in tracing the source of infection and understand the epidemiological relationships among isolates of environmental, fish, other domestic animals or human origins.     

A method for the prediction of multitrait breeding values for use in stochastic simulation to compare progeny-testing schemes, with large progeny groups for proven sires

A method of approximating estimated breeding values (EBV) from a multivariate distribution of true breeding values (TBV) and EBV is proposed for use in large-scale stochastic simulation of alternative breeding schemes with a complex breeding goal. The covariance matrix of the multivariate distributions includes the additive genetic (co)variances and approximated prediction error (co)variances at different selection stages in the life of the animal. The prediction error (co)variance matrix is set up for one animal at a time, utilizing information on the selection candidate and its offspring, the parents, as well as paternal and maternal half- sibs. The EBV are a regression on TBV taking individual uncertainty into account, but with additional 'free' variation drawn at random. With the current information included in the calculation of the prediction error variance of a selection candidate, it is concluded that the method can be used to optimize progeny-testing schemes, where the progeny-tested sires are utilized with large progeny groups, e.g. through artificial insemination.     

Virus survival in slurry: analysis of the stability of foot-and-mouth disease, classical swine fever, bovine viral diarrhoea and swine influenza viruses

Farm slurry can be highly contaminated with viral pathogens. The survival of these pathogens within slurry is important since this material is often distributed onto farm land either directly or after heat treatment. There is clearly some risk of spreading pathogens in the early stages of an outbreak of disease before it has been recognized. The survival of foot-and-mouth disease virus, classical swine fever virus, bovine viral diarrhoea virus and swine influenza virus, which belong to three different RNA virus families plus porcine parvovirus (a DNA virus) was examined under controlled conditions. For each RNA virus, the virus survival in farm slurry under anaerobic conditions was short (generally ≤ 1 h) when heated (to 55°C) but each of these viruses could retain infectivity at cool temperatures (5°C) for many weeks. The porcine parvovirus survived considerably longer than each of the RNA viruses under all conditions tested. The implications for disease spread are discussed.     

Capsid coding sequences of foot-and-mouth disease viruses are determinants of pathogenicity in pigs

The surface exposed capsid proteins, VP1, VP2 and VP3, of foot-and-mouth disease virus (FMDV) determine its antigenicity and the ability of the virus to interact with host-cell receptors. Hence, modification of these structural proteins may alter the properties of the virus.In the present study we compared the pathogenicity of different FMDVs in young pigs. In total 32 pigs, 7-weeks-old, were exposed to virus, either by direct inoculation or through contact with inoculated pigs, using cell culture adapted (O1K B64), chimeric (O1K/A-TUR and O1K/O-UKG) or field strain (O-UKG/34/2001) viruses. The O1K B64 virus and the two chimeric viruses are identical to each other except for the capsid coding region.Animals exposed to O1K B64 did not exhibit signs of disease, while pigs exposed to each of the other viruses showed typical clinical signs of foot-and-mouth disease (FMD). All pigs infected with the O1K/O-UKG chimera or the field strain (O-UKG/34/2001) developed fulminant disease. Furthermore, 3 of 4 in-contact pigs exposed to the O1K/O-UKG virus died in the acute phase of infection, likely from myocardial infection. However, in the group exposed to the O1K/A-TUR chimeric virus, only 1 pig showed symptoms of disease within the time frame of the experiment (10 days). All pigs that developed clinical disease showed a high level of viral RNA in serum and infected pigs that survived the acute phase of infection developed a serotype specific antibody response. It is concluded that the capsid coding sequences are determinants of FMDV pathogenicity in pigs.     

The effects of kale (Brassica oleracea ssp. acephala), basil (Ocimum basilicum) and thyme (Thymus vulgaris) as forage material in organic egg production on egg quality

1. In organic egg production, forage material as part of the diet for laying hens is mandatory. The purpose of the present study was to examine the effect of feeding with forage materials including maize silage, herbs or kale on egg production and various egg quality parameters of the shell, yolk colour, egg albumen, sensory properties, fatty acid and carotenoid composition of the egg yolk.

2. A total of 5 dietary treatments were tested for 5 weeks, consisting of a basal organic feed plus 120?g/hen.d of the following forage materials: 1) maize silage (control), 2) maize silage incl. 15?g/kg basil, 3) maize silage incl. 30?g/kg basil, 4) maize silage incl. 15?g/kg thyme, or 5) fresh kale leaves. Each was supplied to three replicates of 20 hens. A total of 300 hens was used.

3. Feed intake, forage intake and laying rate did not differ with treatment, but egg weight and egg mass produced increased significantly with the kale treatment.

4. The egg shell strength tended to be higher with the kale treatment, and egg yolk colour was significantly more red with the kale treatment and more yellow with basil and kale treatments. The albumen DM content and albumen gel strength were lowest with the thyme treatment. By sensory evaluation, the kale treatment resulted in eggs with less sulphur aroma, higher yolk colour score, and more sweet and less watery albumen taste. Furthermore, the eggs of the kale treatment had significantly higher lutein and β-carotene content. Also, violaxanthin, an orange xanthophyll, tended to be higher in kale and eggs from hens receiving kale.

5. In conclusion, forage material, especially basil and kale, resulted in increased egg production and eggs of high and differentiable quality.     

Effects of percutaneous needle liver biopsy on dairy cow behaviour

In cattle, percutaneous needle liver biopsy is used for scientific examination of liver metabolism. The impact of the biopsy procedure is, however, poorly investigated. Our aim was to examine the behaviour of dairy cows during and after liver biopsy. Data were collected from 18 dry cows. Percutaneous needle liver biopsies (after administration of local anaesthesia (2% Procaine)) and blood samples were taken during restraining. During the control treatment, animals were restrained and blood sampled. During the biopsy procedure, cows showed increased restlessness (P=0.008), frequency of head shaking (P=0.016), and decreased rumination (P=0.064). After biopsies, tail pressing (P=0.016) and time spent perching (P=0.058) increased. Time spent upright (P=0.10) and number of leg movements (P=0.033) increased during the night as compared to controls. Thus, liver biopsy induced behavioural changes for up to 19h - and particularly for behaviour previously associated with pain. Even though the exact welfare impact of percutaneous needle liver biopsies in cows is not known, and the magnitude of the behavioural changes was limited, pain always has negative effects on animal welfare. Therefore, if the present biopsy procedure - involving several biopsy passes - is to be used, improvement of the anaesthetic protocol as well as the inclusion of analgesics should be considered.     

Yersinia enterocolitica in sheep - a high frequency of biotype 1A

Background

Pigs are regarded as the main reservoir for human pathogenic Yersinia enterocolitica, which is dominated by bioserotype 4/O:3. Other animals, including sheep, have occasionally been reported as carriers of pathogenic strains of Y. enterocolitica. To our knowledge, this is the first study performed in the Nordic countries in which the presence of Y. enterocolitica in sheep is investigated.

Methods

Tonsils and faecal samples collected from sheep slaughtered on the island Gotland (Sweden) from September 2010 through January 2011 were analysed for presence of Y. enterocolitica. In an attempt to maximize recovery, several cultural strategies were applied. Various non-selective media were used and different temperatures and durations of the enrichment were applied before subculturing on Cefsulodin Irgasan Novobiocin (CIN) agar. Presumptive Y. enterocolitica colonies were subjected to urease, API 20E and agglutination test. Yersinia enterocolitica isolates were biotyped, serotyped, and tested for pathogenicity using a TaqMan PCR directed towards the ail-gene that is associated with human pathogenic strains of Y. enterocolitica.

Results

The samples collected from 99 sheep yielded 567 presumptive Y. enterocolitica colonies. Eighty urease positive isolates, from 35 sheep, were identified as Y. enterocolitica by API 20E. Thirty-four of 35 further subtyped Y. enterocolitica isolates, all from faecal samples, belonged to biotype 1A serotype O:5, O:6. O:13,7 and O:10. One strain was Yersinia mollaretii serotype O:62. No human pathogenic strains of Y. enterocolitica were found in the investigated sheep. Other species identified were Y. kristensenii (n = 4), Y. frederiksenii/intermedia (n = 3), Providencia rettgeri (n = 2), Serratia marcescens (n = 1) and Raoultella ornithinolytica (n = 1).

Conclusions

This study does not support the hypothesis that sheep play an important role in transmission of the known human pathogenic Y. enterocolitica in the studied geographical region. However, because there are studies indicating that some strains of Y. enterocolitica biotype 1A may cause disease in humans, the relative importance of sheep as carriers of human pathogenic strains of Y. enterocolitica remains unclear. Tonsils do not appear to be favourable sites for Y. enterocolitica biotype 1A in sheep.     

Spatial differences in occurrence of paratuberculosis in Danish dairy herds and in control programme participation

Paratuberculosis is a chronic infection of economic importance to the cattle industry and a voluntary control programme is offered to Danish dairy farmers. Our objective was to evaluate spatial differences in both control programme participation and paratuberculosis prevalence in Denmark. The study included 4414 dairy herds: 1249 were participating in the control programme, and 1503 were tested for antibodies to Mycobacterium avium subsp. paratuberculosis (MAP). Spatial differences were evaluated by kernel smoothing, kriging, and cluster analysis. Participation was lowest among herds on the island Zealand (≤23%). The risk of a herd being infected with MAP was found to be high on most of Zealand, but the uncertainty of this result was large due to a limited number of tested herds. In the rest of the country, the south western part of the peninsula Jutland had the highest risk of MAP (≥91%). The risk of MAP was also high (86-91%) in the northern part of both Jutland and Funen. The predicted apparent within-herd prevalence was highest (5-8.5%) in some local areas across Jutland, in the north western part of the island Funen, and in the south and western part of Zealand. Scan statistics located the primary cluster of herds with high apparent within-herd prevalence in the western part of Funen. Furthermore, a number of significant clusters were found in Jutland and a single significant cluster in Zealand. Consistency was found between kriging and scan statistics results with respect to location of areas with high apparent within-herd prevalence of MAP. Potential explanations for differences in participation include herd size and local herd health advisers, whereas for example soil characteristics might influence prevalence. Further studies are needed to evaluate these and other risk factors.     

Effect of days in milk and milk yield on testing positive in milk antibody ELISA to Mycobacterium avium subsp. paratuberculosis in dairy cattle

Milk samples are becoming more used as a diagnostic specimen for assessment of occurrence of antibodies to Mycobacterium avium subsp. paratuberculosis (MAP). This study assessed the effect of days in milk (DIM) and milk yield on testing positive in a commercial MAP specific milk antibody ELISA among 222,774 Danish Holstein cows. Results showed that odds of testing positive on 1-2 DIM were 9-27 times higher than the rest of lactation, where the chance of testing positive varied less. The reason is most likely a high concentration of non-specific antibodies in colostrum. Consequently, samples from the first couple of DIM should be excluded from MAP testing until further information on their significance is established. Milk yield also had a significant effect on odds of testing positive due to its diluting effect. Inclusion of milk yield in the interpretation of test results could improve the diagnostic value, resulting in more predictable patterns corresponding to progression of infection.